Abstract 1649: Impact of Hormone Replacement Therapy on Myocardial Fatty Acid Metabolism
Background: Studies in experimental animals demonstrate that estrogen (E) increases myocardial fatty acid oxidation (MFAO). Recently, we reported that myocardial oxygen consumption (MVO2) as well as MFAO were increased in post-menopausal women receiving E, and that progesterone appeared to attenuate this effect. However, the study was retrospective.
Hypothesis/Objectives. To determine, prospectively, if short-term administration of E, alone or in combination with progesterone (EP), will alter MVO2 or MFAO in post-menopausal women.
Methods. Fifteen post-menopausal women (age 63 ± 7 yrs) not previously on hormone replacement therapy (HRT) underwent quantitative assessment of myocardial blood flow (MBF), MVO2, and fractional fatty acid uptake (MFAuptake) as well as overall fatty acid utilization (MFAU) and MFAO using positron emission tomography with 15O-water, 11C-acetate and 11C-palmitate, respectively. Rate pressure product (RPP) was used to estimate cardiac work. Measurements were performed at baseline and after 3-days of estradiol (0.3 mg/day via transdermal patch) and either progesterone (200 mg/day orally) or placebo.
Results: After E or EP, both MBF and MVO2 were unchanged from baseline.
Conclusions: Short-term E therapy lowers plasma FFA and tends to lower overall MFAU or MFAO independent of cardiac work. Combined EP administration increases MFAU and MFAO relative to the amount of cardiac work performed. These changes appear to be mediated by peripheral changes in plasma FFA. The long-term effects of HRT on cardiac metabolism and its impact on cardiac risk profile and function remains to be determined